1. Field of the Invention
The present invention relates to power tools, particularly to hand-held vacuum-compression type percussion tools used in the construction industry for drilling holes, demolition of old buildings, pavement breaking, etc.
2. Description of Prior Art
The major problem experienced by the manufacturers of hand-held impact and percussion power tools is to find a compromise among three contradictory requirements, i.e., to provide high energy of impact, light weight of the power tool, and reduced level of vibrations on the power tool's housing. These requirements are dictated by strict sanitary norms.
However, the three requirements mentioned are interrelated so that satisfaction of one of them results in impairment of the others. For example, an increase in the impact energy leads to an increase in weight and level of vibrations. Attempts have been made previously to solve these problems by developing new improved hand-held percussion power tools.
One vacuum compression type power tool aimed at the solution of the above problem is described in my USSR Author's Certificate No. 338,629 of May 1972. This mechanism allows an essential reduction in the level of vibrations due to an increase in the length of the working chamber (i.e., the length of the "air cushion"). This is possible because the increase in the length of the working chamber leads to a reduction in the maximum pressure which normally is the major source of vibrations.
Although the above-mentioned power tool partially solves the problem of vibrations, this solution becomes possible at the cost of overall dimensions and weight. This involves not only mere increase in the length of the working chamber, but also leads to an increase in the diameter of the working chamber cylinder, length of the crank mechanism, etc.